Electronics > RF, Microwave, Ham Radio

Antennas for experimentation

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joeqsmith:
Taking the same Vivaldi and moving to a half meter away from the reference antenna does have an effect on the pattern.  Considering that I am testing these in my home lab it's actually closer than I would have expected.   Shown from two different viewing angles along with a low res 2D plot of the same setup.    Where the SlimJimII was tested a bit over 900MHz,  this Vivaldi is being tested at 2.4GHz.   

The low cost VNAs don't have very good noise specs and moving it further away could be a problem.  My Signal Hound would do a better job making these measurements but it's fun playing with this $120 unit.    The LiteVNA's firmware limits measurements to 9.3GHz.  I have included data comparing it's noise floor against my old Agilent PNA, both using a 1k IF and again with the PNA set to 100Hz.   Also shown is the SA with nothing but a 10dB attenuator attached to it, using the realtime mode with a 2.4GHz center.  Note it still picks up interference from my router.   

Article using a drone to map the radiation pattern.   
https://signalhound.com/news/antenna-measurement-and-characterization-with-uavs/

joeqsmith:
May not look as pretty,  but an effective demo showing the radiation pattern of a dipole.   



Walter Lewin Electromagnetic Waves, Solutions to Maxwell's Equations, Polarization

joeqsmith:
Attempting to use the LiteVNA to sweep an X-band horn.   :-\    It's a tradeoff.  The performance of the Lite is pretty poor but still, $120.

Thedrunkenflea:
Very interesting stuff - i might have found my next project or two!  :-+

joeqsmith:
Looking forward to seeing what you come up with.   

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